Okay.
Lets say activeEntries is the number of entries in your list.
To display those entries, (and not the whole array as gibsonrocker800 explained) you must use a for loop:
public static void displayAll(){
for (int i = 0; i < activeEntries; i++){
System.out.println("First name: " + firstName[i]);
System.out.println("Last name: " + lastName[i]);
System.out.println("Telephone Number: " + telephoneNumber[i]);
System.out.println("Enrolment Number: " + enrolmentNumber[i]);
}
}
Do you follow?